About 2,500 One Communications customers still using 2G phones or SIM cards are being urged to upgrade before the company shuts down its 2G network on October 31.
Mobile Chief Operating Officer Randall Hewitt said affected customers have already been contacted through SMS campaigns and other outreach efforts.
"We are providing free handsets and free SIM upgrades for customers who are impacted," Hewitt said.
He said reaching the remaining customers has been challenging despite targeted campaigns and caravans, recalling one outreach effort where about 800 customers with 2G SIMs were invited to a location, but only three turned up during the entire day.
The move forms part of One Communications' wider effort to modernise its mobile network and move away from older technology while boosting the services customers receive.
Chief Executive Officer Abraham Smith said the company is increasing capacity at existing sites to improve speeds during periods of high usage between 7pm and 9pm.
"So what we're doing now is this year we've been working on both of those things, on increasing the bandwidth on the sites to support additional speed," Smith said.
He said 35 sites, primarily in heavily populated areas, have already received capacity upgrades, and customers there are experiencing higher speeds during busy periods, though data consumption has outpaced the company's expectations.
"We're actually now trying to accelerate next year's additions because we're seeing where the demand has outpaced even our expectations, the data consumption," Smith said.
The company is also completing its transition from 2G to LTE at selected sites while planning additional sites to improve coverage across the country. Smith said the company will no longer invest in developing 2G or 3G technology.
"We won't do any more 2G or 3G development in the country. All the further development will be on LTE," he said.
The upgrades form part of a broader capital investment programme, with One Communications investing about $25 million this year across its mobile, fixed, subsea and core networks. Smith said the current phase is being implemented under a three-year plan, with longer-term coverage plans also being developed.

One Communication CEO Abraham Smith